1. Field of the Invention
The invention relates to a vehicle pop-up hood apparatus that lifts an engine hood under predetermined conditions.
2. Description of the Related Art
In a vehicle pop-up hood apparatus in which a hinge arrangement disclosed in WO01/23226A1 is used, a bonnet (engine hood) is connected to a body through a hinge mechanism. In the hinge mechanism, one end of a middle leaf (link member) is connected to a body-side lower leaf so as to be pivotable about a first pivot, and the other end of the middle leaf is connected to a bonnet-side upper leaf so as to be pivotable about a second pivot. The upper leaf and the middle leaf are integrally connected to each other through a clip mechanism. Under normal conditions, the middle leaf pivots about the first pivot when the bonnet is opened or closed.
When an air bag disposed further forward than the link mechanism and below the bonnet is activated, an air bag deploys, and the bonnet receives the lifting force from the bag, the connection between the upper leaf and the middle leaf by means of the clip mechanism is broken, and the bonnet ascends in a manner such that the bonnet pivots about a front end latch.
In the configuration disclosed in WO01/23226A1, the clip mechanism couples the upper leaf and the middle leaf on the rear side of the second pivot under normal conditions. However, the position at which the air bag pushes up the bonnet is on the front side of the second pivot. In other words, the position at which the air bag pushes up the bonnet is on the side opposite to the position at which the upper leaf and the middle leaf are coupled with respect to the second pivot.
Thus, the direction of the turning force about the second pivot caused when the air bag pushes up the bonnet is opposite to the direction of the turning force required to break the connection, established by the clip mechanism, between the upper leaf and the middle leaf. Accordingly, when such a configuration is adopted, it is necessary to give the bonnet a sufficient strength by providing reinforcement, for example, so that the bonnet is not bent by a pushing force when the bonnet is lifted by the pushing force exerted by the air bag.